The long term goal of this project is to learn the molecular components responsible for survival, process outgrowth and formation of synaptic connections during postnatal development of the retina. This proposal describes studies that examine the interactions between purified glial cells and purified retinal ganglion cells, isolated at a time in development as the ganglion cells begin to make synaptic connections. Use of purified cell populations allows us to assay for and isolate trophic factors, contaminating cells are eliminated, which may themselves produce trophic factors, compete for factors that are in limited supply, or produce factors which inhibit neuronal growth. Monoclonal antibodies were developed, which recognize surface antigens on specific subclasses of cells; these were utilized to isolate homogenous neuronal and glial cells by antibody-mediated plate adhesion from rats of developmentally interesting ages. With the use of this reduced system, we will study the ability of glial cells from retina, optic nerve, and target superior colliculus to produce trophic factors that support the long-term survival of retinal ganglion cells. Subsequently, immunologic and molecular biologic approaches will be used to identify and characterize the molecules involved. The immediate objectives of this study are: (1) to purify specific subsets of retinal and tectal cells which interact with retinal ganglion cells, (ii) to study mechanisms of astroglial support of retinal ganglion cell survival, and (iii) to study the physiologic functions of identified neurotrophic polypeptides which support RGC survival.